One of the charges of the local National Weather Service office in Mt. Holly, NJ, is issuing winter storm watches and warnings. A Winter storm watch means that heavy snow or ice is possible in the next 12 to 36 hours, while a winter storm warning means that heavy snow or ice is expected within the next 6 to 24 hours.

With snow, the criteria for watches and warnings depends a bit on where you live. Five inches of snow is the threshold for issuing a watch or warning in Delaware, southern New Jersey, much of eastern Maryland, as well as Delaware and Philadelphia counties in Pennsylvania.
North of those areas, 6 inches of snow must be expected for a watch or warning to be issued.

And although we've had some relatively mild, snow-free winters lately, recall that just last
March, we did have a 5-inch snowstorm.